Regarding the PSPGo, here are the launches for portable systems over the last 10 years, according to the tracker sinobi, which is really the 3rd preferred tracker after media-create and famitsu, but its what we got:
1998.10.21 (Game Boy Color) - 155,774
2001.03.21 (Game Boy Advance) - 611,504
2003.02.14 (Game Boy Advance SP) - 117,859
2005.09.13 (Game Boy Micro) - 148,117
1998.10.28 (Neo Geo Pocket) - 21,471
1999.03.19 (Neo Geo Pocket Color) - 18,809
1999.03.04 (WonderSwan) - 102,655
2000.12.09 (WonderSwan Color) - 145,975
2002.07.12 (SwanCrystal) - 30,692
2004.11.21 (Nintendo DS) - 441,485
2006.03.02 (Nintendo DS Lite) - 67,653
2008.11.01 (Nintendo DSi) - 170,779
2004.12.12 (PSP-1000) - 166,074
2007.09.20 (PSP-2000) - 263,538
2008.10.16 (PSP-3000) - 155,720
2009.11.01 (PSP go) - 28,275
Note: DSL was supply constrained for a little while after launch.